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June 1997 Monthly Report <br /> Page 5 <br /> 34) and Animas River in Silverton (A-68) on June 10, 1997. <br /> These results are included on the attached summary sheets. <br /> The provisional flow from the outside gage at A-72 for the <br /> June 10, 1997 sample was 749 cfs which is in the high flow <br /> category (Q > 300 cfs) . <br /> The reported dissolved zinc value is 347 ug/l which is the <br /> average of results from two labs. <br /> Subbasin zinc concentrations at the gaging stations on June <br /> 10, 1997 were as follows; Cement Creek (C-48) 770 ug/l, <br /> Mineral Creek (M-34) 190 ug/1 and Animas River (A-68) 450 <br /> ug/l. These zinc values appear to be in the normal range for <br /> the flows observed although the Animas River may be 50-100 <br /> ug/1 high for this time of year. <br /> The index number for the June sample is calculated as follows: <br /> Xi = 347 <br /> Xf = 306 <br /> Sf = 104 <br /> Ni = (Xi-Xf)/Sf <br /> Ni = (347-306)/104 <br /> Ni = +0. 39 <br /> The index number graph and updated reporting table are attached. <br /> Evaluation of the normalized data: <br /> The index value of +0. 39 for June indicates this result was <br /> higher than the mean of the reference data set for the high <br /> flow class but significantly lower than the index numbers <br /> calculated for December, 1996 through May, 1997. A meeting <br /> has been scheduled in July to discuss the monitoring results <br /> previously reported. <br /> A 12 period moving average graph is attached. The calculated <br /> moving average value for June was 1. 000 which is slightly <br /> higher than the moving average for May (0.947) . Unless <br /> significant improvements in stream water quality are realized <br /> from Sunnyside 's projects in 1997 , the 12 period moving <br /> average will stay around 1. 000 until December, 1997 or <br /> January, 1998 which is when the high values that make up this <br /> average can be replaced with new lower values. It is not <br /> likely that the 12 period moving average index number will or <br /> could be below +0. 577 before April or May of 1998, although a <br /> dropping trend could be observed by January 1998 if <br /> Sunnyside is correct in the assumption that the rise in zinc <br /> concentrations observed from December 1996 through May 1997 <br />